During recent years requirements for the sterilization of surgical instruments have been intensified due to increased knowledge of the risks of infection in public health and sick care. The HIV-problems contribute to the enforcement of stricter requirements for sterilization, especially of instruments for rectal use.
Surgical instruments which are utilized to devitalize tissues, such as internal hemorroids, by ligation, a so-called elastic ligature, represent one type of proctologic instrument which is affected by these stricter requirements for sterilization. Different types of instruments for ligating of internal hemorrhoids are known. All these instruments are meant to be used several times, that is, they are designed to be re-utilized several times with a sterilization in between.
The method of sucking a hemorrhoid into a cylinder with an elastic cord mounted around it is previously known, e.g. from U.S. Pat. No. 4,257,419. A displaceable outer cylinder is arranged on the suction cylinder and an actuating element is adapted, via a transmission mechanism, to displace the outer cylinder in such a way that the cord is pushed beyond the suction cylinder, whereby it will enclose the hemorrhoid which is inserted in the suction cylinder.
U.S. Pat. No. 3,382,873 discloses a more simple construction of an instrument designed for the same purpose. This instrument is intended to be used together with a gripping instrument which is lead through the concentric cylinders to grip and introduce a hemorrhoid into the cylinders. When the actuating element is brought into force, the angled inner cylinder is displaced backwards along its longitudinal axis by means of interacting cam surfaces and the elastic cord is released. The hemorrhoid is introduced into the cylinders by means of the extra gripping instrument. This instrument is therefor not constructed to interact with a vacuum source.
U.S. Pat. No. 3,760,810 discloses several different embodiments of an instrument for the ligation of hemorrhoids. The embodiments all have in common that the instrument is made of two concentric tubes with an elastic cord arranged around the front part of one of the tubes and that one tube is displaceable on the other. One of these tubes is connected to a fixed handle and the other is connected to a movable actuating element, via a transmission mechanism. In one embodiment the instrument can be connected to a vacuum source, while in the other embodiments an interacting gripping tool must be utilized. One embodiment discloses an instrument (see FIG. 12-14) which permits one unit, comprising the two concentric tubes, to be disengaged from the handle. This unit can be exchanged and consequently one part of the instrument can be disposable. The previously known instruments have a number of disadvantages:
Instruments that necessitate interaction with a gripping instrument are difficult to handle since the operating surgeon must use both hands, one for the instrument and the other for the assisting tool. In addition, the proctoscope which is used for orientation in the cavity in the human body must be held by an assistant, which involves a difficult coordination between the instruments, with prolonged operation time as a consequence.
All previously known solutions disclose constructions which are complicated and contain a large number of interacting parts. The transmission mechanism between the activating element and the discharge-cylinder in particular contains several integral parts. The different parts are often made of metal. The known constructions are thus made for reutilization with a sterilization in between.
To make one part of the instrument disposable, as shown in U.S. Pat. No. 3,760,810 described above, implies that the different parts must be furnished with connecting devices, in this case a dovetailed guide connection, which makes the manufacturing complicated and the instrument more expensive. Furthermore, the part of the instrument which will be reutilized has to be sterilized between every utilization.
In conclusion, it can be claimed that none of the previously known instruments discloses a construction which makes it suitable as a disposable instrument.